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June 27, 2011

Snake Venom Symptoms Slowed With Ointment

by Sam Savage

Researchers in Australia have found that a chemical compound typically used on heart patients may raise chances of survival for snakebite victims.

The study, published in Nature Medicine, claims chemical nitric oxide can slow down, by as much as 50 percent, the time it takes for snake venom to enter the bloodstream allowing time for victims to seek medical help, said lead author Dirk van Helden, professor at the School of Biomedical Sciences, University of Newcastle in Australia.

Reuters reports that although poisonous snakes are responsible for the deaths of only a handful of people in the United States each year, the World Health Organization (WHO) places the global number at about 100,000 people.

Bulky proteins from the venom of some snakes do not infiltrate the bloodstream immediately but find their way through the lymphatic system to the heart. Ideally, a pressure bandage is applied in hopes of slowing the venom's spread until the victim can receive antivenom medicine.

Antivenom is essentially antibodies that lock onto and neutralize the poison but many victims are unable to receive antivenom in time especially if the puncture is on the face or near the neck, Science Now reports. Van Helden and colleagues attempted to find a chemical method to detain the venom.

The researchers settled on an ointment that contains glyceryl trinitrate, the compound better known as nitroglycerin that doctors have used to treat everything from tennis elbow to angina. The ointment releases nitric oxide, causing the lymphatic vessels to clench.

The researchers first injected volunteers in the foot with a harmless radioactive mixture that, like some snake toxins, moves through the lymphatic vessels. In control subjects that didn't receive the ointment, the mixture took 13 minutes to climb to the top of the leg.

The time for the venom to take effect was lengthened to 54 minutes if the researchers immediately smeared the ointment around the injection site, the team reported. Further experiments using real toxins in rats yielded roughly the same results.

Finally, the researchers compared the survival time in rats injected with venom that were treated with the ointment against those that were not, and found that the nitric oxide rats kept breathing 50 percent longer, AFP reports.

"These results point to a new method of snakebite first aid that may also be useful for bites to the torso or head," the researchers concluded.